1. Field of the Invention
The present invention relates to a multilayer wiring substrate, a probe card equipped with the multilayer wiring substrate, and a method for manufacturing the multilayer wiring substrate.
2. Description of the Related Art
Nowadays, multilayer wiring substrates, on the main surfaces of which components such as ICs are mounted, are widely used. The multilayer wiring substrate includes a plurality of wiring lines extending from the mounting surface to the rear surface thereof. Each of the plurality of wiring lines includes a plurality of via conductors, which are electrically connected to one another.
Multilayer wiring substrates are described, for example, in Japanese Unexamined Patent Application Publication No. 2008-300482 and Japanese Unexamined Patent Application Publication No. 2008-164577. In these multilayer wiring substrates, the pitch of the wiring lines on the mounting surface is smaller than that on the rear surface.
Nowadays, the size of electronic components such as ICs to be mounted on the multilayer wiring substrates is further being reduced. As the size of the electronic components is reduced, there is a demand for reduction of the pitch of the wiring lines on the mounting surface.